Method for encoding video information and method for decoding video information, and apparatus using same

ABSTRACT

According to one embodiment of the present invention, a video information encoding method comprises: a step of predicting information of the current coding unit to generate prediction information; and a step of determining whether the information of the current coding unit coincides with the prediction information. If the information of the current coding unit coincides with the prediction information, a flag indicating that the information of the current coding unit coincides with the prediction information is encoded and transmitted. If the information of the current coding unit does not coincide with the prediction information, a flag indicating that the information of the current coding unit does not coincide with the prediction information is encoded and transmitted and the information of the current coding unit is encoded and transmitted. In the step of generating prediction information, the prediction information may be generated using the information on the coding unit adjacent to the current coding unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 13/977,520having a 371(c) date of Jun. 28, 2013, now U.S. Pat. No. 9,955,155issued on Apr. 24, 2018, which is a U.S. national stage application ofInternational Application No. PCT/KR2011/010379 filed on Dec. 30, 2011,which claims the benefit of Korean Patent Application Nos.10-2010-0140721 filed on Dec. 31, 2010, and 10-2011-0147083 filed onDec. 30, 2011, in the Korean Intellectual Property Office, the entiredisclosures of which are incorporated herein by reference for allpurposes.

TECHNICAL FIELD

The present invention relates to a method and an apparatus forpredicting and coding coding information in high efficiency video coding(HEVC).

BACKGROUND ART

Recently, a broadcast service having high definition (HD) resolution(1280×1024 or 1920×1080) has been expanded in the country and all overthe world. Today, many users have been familiar with high-resolution andhigh-quality images.

Therefore, many organizations have been attempted to developnext-generation image devices. In addition, as the interest in ultrahigh definition (UHD) having a resolution four times higher than that ofHDTV next to HDTV has been increased, moving picture standardizationorganizations have recognized the necessity for a compression technologyfor a higher-resolution and higher-definition video.

In connection with this, the next-generation image devices have requireda new standard capable of acquiring many advantages in terms of afrequency band or storage while maintaining the same image quality usingcompression efficiency higher than that of H.264/AVC used for HDTV,mobile phones, Blue-ray player.

A moving picture experts group (MPEG) and a video coding experts group(VCEG) commonly standard high efficiency video coding (HEVC) that is anext-generation video codec and are to code images including an UHDimage with compression efficiency twice higher than that of H.264/AVC.The next-generation video codec (HEVC) is to provide the high-qualityimage at a frequency lower than the current even in HD and UHD image anda 3D broadcast and mobile communication network.

The HEVC was adopted to measure standard performance of the codec namedas Test Model Under Consideration (TMuC) through a contribution of eachorganization after Joint Collaboration Team Video Coding (JCT-VC)conference is first held in April, 2010.

Meanwhile, various technologies have been adopted so as to increase thecoding/decoding efficiency in the HEVC. How to process the informationnecessary for prediction/conversion/quantization, or the like, so as toperform coding of the current CU is problematic.

DISCLOSURE Technical Problem

The present invention provides a method and an apparatus for improvingcompression efficiency of coded information, in a high-efficiency movingpicture coding/decoding technology.

The present invention also provides a method and an apparatus forcoding/decoding information on coding unit by using neighborinformation, in a high-efficiency moving picture coding/decodingtechnology.

The present invention also provides a method and an apparatus forcoding/decoding information on coding unit by using neighbor informationwhen the information on the coding unit is not the same as the neighborinformation, in a high-efficiency moving picture coding/decodingtechnology.

The present invention also provides a method and an apparatus forremoving redundancy of information between CUs by predicting and codinginformation on independently coded CUs by neighboring coding unitswithin the same frame, a coding unit or a prediction structure within areference frame, in a high-efficiency moving picture coding/decodingtechnology.

Technical Solution

In an aspect, there is provided a method for coding image information,including: generating prediction information by predicting informationon a current coding unit; and determining whether the information on thecurrent coding unit is the same as the prediction information, whereinwhen the information on the current coding unit is the same as theprediction information, a flag indicating that the information on thecurrent coding unit is the same as the prediction information is codedand transmitted, and when the information on the current coding unit isnot the same as the prediction information, the flag indicating that theinformation on the current coding unit is not the same as the predictioninformation and the information on the current coding unit are coded andtransmitted, and at the generating of the prediction information, theprediction information is generated by using the information on thecoding unit neighboring to the current coding unit.

The information on the coding unit neighboring to the current codingunit may be the information on the coding unit corresponding to thecurrent coding unit within a reference frame.

The information on the coding unit neighboring to the current codingunit may be a split flag regarding the coding unit corresponding to thecurrent coding unit within the reference frame, and the determiningwhether the information on the current coding unit is the same as theprediction information may determine whether the split flag regardingthe current coding unit for each depth is not the same as the splitinformation regarding the coding unit corresponding to the currentcoding unit within the reference frame.

The information on the coding unit neighboring to the current codingunit may be the information on the coding unit neighboring to thecurrent coding unit within a frame to which the current coding unitbelongs.

The information on the coding unit neighboring to the current codingunit may be the information on the prediction structure within the frameto which the current coding unit and the neighboring coding unit belongand the determining whether the information on the current coding unitis the same as the prediction information may determine that theinformation on the current coding unit is the same as the predictioninformation when the current coding unit performs inter-pictureprediction by using two lists referring to two frames, respectively,that are temporally previous and subsequent and determine that theinformation on the current coding unit is not the same as the predictioninformation, when the current coding unit performs the inter-pictureprediction without using two lists referring to two frames,respectively, that are temporally previous and subsequent.

When the information on the current coding unit is not the same as theprediction information, the list to be referred and a reference indexmay be coded and transmitted as the information on the current codingunit.

When the information on the current coding unit is not the same as theprediction information, a flag indicating that the information on thecurrent coding unit is not the same as the prediction information and adifference between the information on the current coding unit and theprediction information may be coded and transmitted.

When the information on the current coding unit is not the same as theprediction information, a codeword may be generated excluding theprediction information from the coding information selected as theinformation on the current coding unit to code the information on thecurrent coding unit.

When the information on the current coding unit is not the same as theprediction information, probability for the information on the currentcoding unit may be again generated based on the prediction informationto code the information on the current coding unit.

In another aspect, there is provided a method for decoding imageinformation, including: decoding a prediction flag indicating whetherinformation on a current coding unit is the same as predictioninformation predicted from information on a coding unit neighboring tothe current coding unit; and determining whether the information on thecurrent coding unit is the same as the prediction information based onthe decoded prediction flag, wherein when the information on the currentcoding unit is the same as the prediction information, the predictioninformation is used as the information on the current coding unit, andwhen the information on the current coding unit is not same as theprediction information, the information on the current coding unit isdecoded.

The information on the coding unit neighboring to the current codingunit may be the information on the coding unit corresponding to thecurrent coding unit within a reference frame.

The information on the coding unit neighboring to the current codingunit may be a split flag regarding the coding unit corresponding to thecurrent coding unit within a reference frame.

The information on the coding unit neighboring to the current codingunit may be the information on the coding unit neighboring to thecurrent coding unit within a frame to which the current coding unitbelongs.

The information on the coding unit neighboring to the current codingunit may be the information on the prediction structure within the frameto which the current coding unit and the neighboring coding unit belong,and at the determining whether the information on the current codingunit is the same as the prediction information, when the information onthe current coding unit is the same as the prediction information,inter-picture prediction may be performed by using two lists referringto two frames, respectively, that are temporally previous and subsequentfor the frame to which the current coding unit belongs.

At the determining whether the information on the current coding unit isnot the same as the prediction information, if it is determined that theinformation on the current coding unit is not the same as the predictioninformation, the inter-picture prediction may be performed based on areference list and a reference index separately transmitted.

When the information on the current coding unit is not the same as theprediction information, the information on the current coding unit maybe decoded based on the prediction information.

The difference between the prediction information and the information onthe current coding unit may be decoded and a value added to theprediction information may be used as the information on the currentcoding unit.

The information on the current coding unit may be obtained by selectingany one of the candidate information excluding the predictioninformation from the candidate information selected as the informationon the current coding unit.

Probability for the information on the current coding unit may be againgenerated based on the prediction information to decode the informationon the current coding unit.

Advantageous Effects

As set forth above, the embodiments of the present invention can improvethe coding efficiency for the information on the coding unit in thehigh-efficiency video coding/decoding technology.

The embodiments of the present invention can remove the redundancy ofinformation between the CUs by predicting and coding the information onindependently coded CUs by the neighboring coding unit within the sameframe, the coding unit or the prediction structure within the referenceframe, when the image is coded in the coding unit (CU) unit in thehigh-efficiency video picture coding/decoding technology.

The embodiments of the present invention can code and decode theinformation on the current coding unit by using the neighboringinformation in the high-efficiency video coding/decoding technology.

DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram schematically showing an example of a coderstructure.

FIG. 2 is a diagram schematically showing an example of a decoderstructure.

FIG. 3 is a diagram schematically explaining one split in a CU unit whenprocessing data.

FIG. 4 is a diagram showing in detail a process of splitting a CU withinan LCU.

FIG. 5 is a diagram schematically explaining split flag established whenthe split is performed.

FIG. 6 is a diagram schematically showing a hierarchical structurebetween frames applied when inter-picture prediction (inter prediction)is performed.

FIG. 7 is a diagram schematically explaining a correspondencerelationship between CU within the current frame and a CU of a referenceframe.

FIG. 8 is a flow chart schematically explaining an example of a methodfor predicting and coding the information on the current CU by usinginformation on a neighboring CU in a system to which the embodiment ofthe present invention is applied.

FIG. 9 is a flow chart schematically explaining an example of a methodfor predicting and coding the information on the current CU by using theinformation on the neighboring CU in a system to which the embodiment ofthe present invention is applied.

FIG. 10 is a diagram schematically explaining a method for transmittingsplit flag.

FIG. 11 is a diagram schematically explaining a method for predictingthe split flag regarding the current LCU by using the split flagregarding LCU corresponding to the current LCU in the reference frame,in the system to which the present invention is applied.

FIG. 12 is a diagram schematically explaining a method for predictingthe split flag regarding the current LCU by using split flag regardingLCU corresponding to the current LCU in the reference frame, in thesystem to which the present invention is applied.

FIG. 13 is a diagram schematically showing the current CU and theneighboring CU within the same frame.

FIG. 14 is a flow chart for schematically explaining a method forpredicting and coding information on a current CU through CU neighboringto the current CU when coding the information on the current CUaccording to the embodiment of the present invention.

FIG. 15 is a flow chart schematically explaining another example of amethod for predicting and decoding the information on the current CU byusing the information on the neighboring CU in a system to which theembodiment of the present invention is applied.

FIG. 16 is a diagram explaining one predicting and coding theinformation on the current CU by using the neighboring CU.

FIG. 17 is a flow chart schematically explaining an example of a methodfor predicting and coding the information on the current CU from theprediction structure when coding the information on the current CUaccording to the embodiment of the present invention.

FIG. 18 is a flow chart schematically explaining an example of a methodfor predicting and decoding the information on the current CU by usingthe prediction structure to which the embodiment of the presentinvention is applied.

FIG. 19 is a diagram explaining one predicting and coding theinformation on the current CU by the prediction structure in a frameunit according to the embodiment of the present invention when includinga hierarchical prediction structure.

FIG. 20 is a flow chart schematically explaining an example of a methodfor decoding reference index prediction information according to theembodiment of the present invention.

FIG. 21 is a diagram showing a schematic configuration of a coder forpredicting and coding the information on the current CU through theinformation on the CU corresponding to the current CU within thereference frame according to the embodiment of the present invention.

FIG. 22 is a diagram showing a schematic configuration of a decoder forpredicting and decoding the information on the current CU through theinformation on the CU corresponding to the current CU within thereference frame according to the embodiment of the present invention.

FIG. 23 is a diagram showing another example of a coder for predictingand coding the information on the current CU through the information onthe CU corresponding to the current CU within the reference frameaccording to the embodiment of the present invention.

FIG. 24 is a diagram showing another example of a decoder for predictingand decoding the information on the current CU through the informationon the CU corresponding to the current CU within the reference frameaccording to the embodiment of the present invention.

FIG. 25 is a diagram schematically showing a configuration of the coderfor predicting and coding the information on the current CU by using theinformation on the neighboring CU within the same frame according to theembodiment of the present invention.

FIG. 26 is a diagram schematically showing a configuration of thedecoder for predicting and decoding the information on the current CU byusing the information on the neighboring CU within the same frameaccording to the embodiment of the present invention.

FIG. 27 is a diagram schematically showing a configuration of the coderfor predicting and coding the information on the current CU through theprediction structure according to the embodiment of the presentinvention.

FIG. 28 is a diagram schematically showing a configuration of the coderfor predicting and decoding the information on the current CU throughthe prediction structure according to the embodiment of the presentinvention.

MODE FOR INVENTION

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. Indescribing exemplary embodiments of the present invention, well-knownfunctions or constructions will not be described in detail since theymay unnecessarily obscure the understanding of the present invention.

It will be understood that when an element is simply referred to asbeing ‘connected to’ or ‘coupled to’ another element without being‘directly connected to’ or ‘directly coupled to’ another element in thepresent description, it may be ‘directly connected to’ or ‘directlycoupled to’ another element or be connected to or coupled to anotherelement, having the other element intervening therebetween. Further, inthe present invention, “comprising” a specific configuration will beunderstood that additional configuration may also be included in theembodiments or the scope of the technical idea of the present invention.

Terms used in the specification, ‘first’, ‘second’, etc. can be used todescribe various components, but the components are not to be construedas being limited to the terms. The terms are only used to differentiateone component from other components. For example, the ‘first’ componentmay be named the ‘second’ component without being departed from thescope of the present invention and the ‘second’ component may also besimilarly named the ‘first’ component.

Furthermore, constitutional parts shown in the embodiments of thepresent invention are independently shown so as to representcharacteristic functions different from each other. Thus, it does notmean that each constitutional part is constituted in a constitutionalunit of separated hardware or software. In other words, eachconstitutional part includes each of enumerated constitutional parts forconvenience. Thus, at least two constitutional parts of eachconstitutional part may be combined to form one constitutional part orone constitutional part may be divided into a plurality ofconstitutional parts to perform each function. The embodiment where eachconstitutional part is combined and the embodiment where oneconstitutional part is divided are also included in the scope of thepresent invention, if not departing from the essence of the presentinvention.

In addition, some of constituents may not be indispensable constituentsperforming essential functions of the present invention but be selectiveconstituents improving only performance thereof. The present inventionmay be implemented by including only the indispensable constitutionalparts for implementing the essence of the present invention except theconstituents used in improving performance. The structure including onlythe indispensable constituents except the selective constituents used inimproving only performance is also included in the scope of the presentinvention.

FIG. 1 is a diagram schematically showing an example of a coderstructure. A coder 100 of FIG. 1 may be a coder supporting highefficiency video coding.

Referring to FIG. 1, a coder 100 receives images and codes the receivedimages by an intra mode or an inter mode to output a bitstream. When thecoding is performed using the intra mode, a switch 130 is switched to anintra and when the coding is performed using the inter mode, the switch130 is switched to an inter mode.

A main flow of a coding process performed in the coder generates aprediction block for a block of the input images and then, obtains adifference between the block of the input images and the predictionblock, thereby performing the coding.

The generation of the prediction block is performed according to theintra mode and the inter mode. In the case of the intra mode, theprediction block is generated by allowing an intra prediction module 120to perform spatial prediction by using already coded neighboring pixelvalues of the current block. In the case of the inter mode, a motionprediction module 105 searches a region that is optimally matched withthe current input block in the reference picture stored in a referencepicture buffer 110 to obtain a motion vector. A motion compensator 125may perform motion compensation by using a motion vector to generate theprediction block.

As described above, a subtractor 160 obtains the difference between thecurrent block and the prediction block to generate a residual block. Thecoding for the residual block is performed in order such as transform ina transform module 135, quantization in a quantization module 140,entropy coding in an entropy encoding module 145 or the like.

The transform module 135 receives the residual block to performtransform and outputs transform coefficients. Further, the quantizingmodule 140 quantizes the transform coefficients according toquantization parameters to output the quantized coefficients. Then, theentropy encoding module 145 performs the entropy coding on the quantizedcoefficients according to probability distribution and outputs theentropy coded coefficients as the bitstream.

In inter-frame prediction coding, the currently coded images may be usedas the reference picture of subsequently input images. Therefore, thereis a need to decode and store the currently coded images. The quantizedcoefficients are dequantized and inversely transformed by passingthrough a dequantization module 150 and an inverse transform module 155.

As shown, the residual block passing through the dequantization and theinverse transform is resynthesized with the prediction image by an adder165 to generate a reconstructed block. A deblocking filter 115 removes ablocking artifact of the reconstructed block generated during the codingprocess and the reference picture buffer 110 stores a deblockedreconstructed image.

FIG. 2 is a diagram schematically showing an example of a decoderstructure. The decoder of FIG. 2 may be a decoder supporting highefficiency video coding.

When performing the coding, the bitstream is output. A decoder 200receives the bitstream and performs the received bitstream by the intramode, thereby outputting the reconstructed images.

In the case of the intra mode, a switch 240 is switched to the intra andin the case of the inter mode, the switch 240 is switched to the inter.

A main flow of a decoding process performed in the decoder generates theprediction block and then, adds a result block of decoding the inputbitstream and the prediction block, thereby generating a reconfiguredblock.

The generation of the prediction block is performed according to theintra mode and the inter mode. In the case of the intra mode, an intraprediction module 250 performs the spatial prediction by using thealready coded neighboring pixel values of the current block, therebygenerating the prediction block. In the case of the inter mode, a motioncompensation module 280 searches the corresponding region in thereference picture stored in a reference picture buffer 270 by using amotion vector to perform the motion compensation, thereby generating theprediction block.

An entropy decoding module 210 performs the entropy decoding on theinput bitstream according to the probability distribution and outputsthe quantized coefficients. The quantized coefficients are dequantizedand inversely transformed by passing through a dequantization module 220and an inverse transform module 230 and are then coupled with theprediction images by an adder 290, thereby generating the reconstructedblock. The blocking artifact of the reconstructed block is removed by adeblocking filter 260 and then, the reconstructed block is stored in areference picture buffer 270.

Meanwhile, the high efficiency video coding/decoding may process datausing, for example, a coding unit (CU) unit for each predetermined unit.The CU may be referred to as a basic block unit processing data.

FIG. 3 is a diagram explaining the CU, wherein FIG. 3 schematicallyexplains one performing the split in the CU unit when processing data.

Referring to FIG. 3, the image is split in an already defined basic CUunit and is then subjected to the coding while splitting the CU. Themost basic CU unit is referred to as a largest coding unit (LCU).Starting to the LCU, the CU may be split into four CUs of which the sizeof the block is reduced half in length and width if necessary Splittingthe CU is determined according to the characteristics of the images atthe coding side. In the case of the complex image, the CU may be splitinto smaller CUs and in the case of the non-complex image, the CU maynot be split into the smaller CUs. Therefore, whether the CU is splitmay be determined according to the efficiency in terms of thecompression efficiency and the image quality.

The information on whether to split the CU is represented by a splitflag. The split flag is included in all the CUs other than the CU in thesmallest unit that cannot be split any more. When a split_flag of thesplit flag is ‘0’, the corresponding CU is not split and when thesplit_flag of the split flag is ‘1’, the corresponding CU ishierarchically split into four small CUs that are bisected in length andwidth, respectively.

A depth is increased by 1 every time the CU is split once. The depth ofthe CUs having the same size may be the same. The maximum depth of theCU may be previously defined and the CU cannot be split at a predefinedmaximum depth or more. Therefore, the depth of split of the CU isincreased by 1 while the CU is split from the LCU having a depth of 0and the CU may not be split up to the maximum depth.

Referring to FIG. 3, when the split_flag of the split flag is 0 for theCU (LCTU) having depth 0, the CU is not split any more and when thesplit_flag of the split flag is 1, the CU may be split into four smallerCUs. In this case, the split small CUs may be differentiated by beingallocated with indexes 0, 1, 2, and 3.

When the split is performed, the depth is increased. An example of FIG.3 shows the case in which the maximum depth is set to be 4. As shown inFIG. 3, when the CU is split up to the maximum depth 4, the CU is nofurther split.

The right drawing of FIG. 3 is a diagram schematically explaining thecase in which the CU is split according to the depth when the LCU is2N×2N pixels (N=64) and the maximum depth is 4. For convenience ofexplanation herein, the case in which the LCU is 128×128 is described byway of example, but the embodiment of the present invention is notlimited thereto and the LCU may be defined by different sizes.

FIG. 4 is a diagram showing in more detail a process of splitting CUwithin LCU.

The case in which the size of LCU 400 is 64×64 pixels and the maximumdepth is 3 will be described with reference to FIG. 4. When the codingis not performed in a unit of 64×64 pixels, ‘1’ indicating the case inwhich the CU is split as the split_flag of the split flag regarding theCU of 64×64 pixels is stored. Therefore, the CU of 64×64 pixels is splitinto four CUs of 32×32 small pixels by half in length and width.

When the CUs 410, 420, and 430 of 32×32 pixels split in the CU of 64×64pixels are no further split, ‘0’ indicating the case in which the CU isnot split as the split-flag of the split flag is stored. In this case,the CUs 410, 420, and 430 may be coded in a unit of 32×32 pixels usingthe intra mode or the inter mode.

When the CU 440 of 32×32 pixels is split in four smaller CUs of 16×16pixels, ‘1’ is stored as the split-flag of the split flag regarding theCU 440 and the four CUs of 16×16 pixels is coded. Even though thepredetermined maximum depth is 3, if the CU of 16×16 pixels is set tothe smallest CU (depth 2), the CU may not be split any more andtherefore, may not include the split flag. When the CU of 16×16 pixelsis not set to be the smallest CU, the 16×16 pixels may be no furthersplit. In this case, ‘0’ is stored as the split flag.

FIG. 5 is a diagram schematically explaining the split flag establishedwhen the split is performed like the example of FIG. 4. Referring toFIG. 5, when the split flag regarding each CU is transmitted in the LCUunit, the split flag regarding the CU of 64×64 pixels is first stored.Meanwhile, when the CU of 64×64 pixels is split, the split flagregarding four CUs of 32×32 pixels subsequent to the split flagregarding the CU of 64×64 pixels is stored. Therefore, in the decoder,the split flag regarding the CU of 64×64 pixels is first confirmed andwhen the CU of 64×64 pixels is split, the split flag regarding the CU of32×32 pixels may be confirmed.

In the example of FIG. 4, the CU 440 is split again. In FIG. 5, thesplit flag regarding CU 440 is instructed by a second split flag atdepth 2. Therefore, after the split flag regarding the CU 440 is stored,the split flag regarding the four CUs of 16×16 pixels split from the CU440 is stored. Next, in the LCU 400 of FIG. 4, the split flag regardingthe CU 420 at the lower left end and the CU 410 at the lower right endis stored in order.

As shown in FIG. 5, when the CU is spilt in the real image, thehierarchical split is performed in the LCU unit. For example, in thecase of FIG. 4, the maximum depth is 3 and therefore, when the depth is3, the CU is no further split. Therefore, the split flag exists only inthe CU when the depth is 0, 1, and 2. The size and the maximum depth ofthe LCU can determine the storage frequency of the split flag regardingthe CU and the size of the CU upon compressing the image and therefore,may be considered as very important information.

FIG. 6 is a diagram schematically showing a hierarchical structurebetween frames applied when inter-picture prediction (inter prediction)is performed. In the high efficiency video coding/decoding, all the CUsallocate the intra mode, that is, an intra frame (I-frame) within aframe for each predetermined frame and quickens an arbitrary access atthe time of reproducing the image.

FIG. 6 shows, by way of example, the case in which the inter-pictureprediction is hierarchically performed by allocating 9 frames into onegroup. In the example of FIG. 6, number 0 frame T0 is coded with theintra frame I0 and number 8 frame T8 is coded by performing theinter-picture prediction through the number 0 frame T0. Next, whennumber 4 frame T4 is coded, the inter-picture prediction may beperformed through the number 0 frame T0 and the number 8 frame T8 thatare temporally previous and subsequent. As described above, the number 2frame is hierarchically coded through the number 0 frame T0 and thenumber 4 fame T4 and number 6 frame T6 is coded through the number 4frame T4 and the number 8 frame T8. Finally, number 1 frame T1 is codedthrough the number 0 frame T0 and the number 2 frame T2, number 3 frameT3 is coded through the number 2 frame T2 and the number 4 frame T4,number 5 frame T5 is coded through the number 4 frame T4 and the number6 frame T6, and finally, number 7 frame T7 is coded through the number 6frame T6 and the number 8 frame T8.

When the coding is performed as described above, the number 1 frame tothe number 8 frame may be coded by determining the intra mode or theinter mode in the CU unit. When the CU is the inter mode, the motioncompensation is performed in the block unit. In this case, each blockperforms the motion compensation through forward prediction (L0prediction) and inverse prediction (L1 prediction). In this case, thecoding may be divided into the case in which the coding is performed byusing only one of the L0 prediction and the L1 prediction and the codingis performed by using both of the L0 prediction and the L1 prediction.Meanwhile, the frame using only the L0 prediction in the frame unit isreferred to as a P frame (prediction frame) and the frame using both ofthe L0 prediction and the L1 prediction is referred to as a B frame(Bi-prediction frame).

Meanwhile, in the high efficiency video coding/decoding, the coding orthe decoding is performed in the CU unit. In this case, most of theinformation is independently coded in the CU unit. Describingdistribution of the information within the CU for each quantizationparameter (QP) at the bitstream, the information on the CU (intraprediction direction information (IntraDir), split flag, skipinformation, motion merge information, coding mode information (Predic),block split flag (Part size), motion prediction information (AMVP),motion difference information (MVD), prediction direction information(Dir), or the like) accounts for a great part in the bitstream.

In addition, as the size of the quantization parameter is large, aweight of coding a transform coefficient is small. As a result, a weightof other information is relatively increased within the CU. Inparticular, when the value of the quantization parameter is largest, theratio of the information on the CU is increased to occupy about 50%. Inthis case, when considering the information (information and the like onwhether the coding is performed in the block unit) used for the codingof the transform coefficient, a bit amount other than the transformcoefficient is 60% or more.

The information is coded by a context based adaptive variable lengthcoding (CAVLC) method or a context based adaptive arithmetic coding(CABAC) method considering peripheral conditions, thereby reducing thebit amount. Currently, when the information is coded, most informationis coded according to a spatial correlation. In a portion of theinformation, the case of using the temporal correlation may exist.Further, the case of performing the coding exists without consideringthe spatial or temporal correlation.

When the information on the CU is coded in consideration of only thespatial correlation, the temporal correlation is higher than the spatialcorrelation for the coded information. In this case, the coding isperformed based on the temporal correlation than the spatialcorrelation, thereby more increasing the coding efficiency for thecorresponding information. In addition, when the coding is performed inconsideration of the spatial correlation and the temporal correlation,the coding efficiency for the corresponding information may be moreincreased.

Therefore, for performing efficient prediction coding for eachinformation on the CU, the information on the CU is applied to thecoding by determining whether the corresponding information has the highspatial correlation or the high temporal correlation.

The coding and decoding may be performed in the CU unit. When the CU iscoded, the coding may be performed by predicting the information on thecorresponding CU through the information on the corresponding CU and theneighboring CU within the same frame when coding the CU. In addition,when the corresponding CU is the inter mode, the coding may be performedby predicting the information on the corresponding CU through theinformation on the CU within the reference frame or the coding may beperformed by predicting the information on the corresponding CU throughthe prediction structure in the frame unit. As described above, thecompression efficiency for the information within the CU may be improvedby using the information on the neighboring CU.

In the case of the high efficiency video coding/decoding, the embodimentof the present invention proposes the method for predicting andcoding/decoding the information on the current CU using the informationon the neighboring CU upon coding/decoding the information on the CU. Inthis case, the neighboring CU to be used may also be the CU temporallyneighboring to the current CU and the CU spatially neighboring to thecurrent CU. In addition, the information on the neighboring CU to beused includes the information on the prediction structure in the frameunit to which the current CU and the CU neighboring to the current CUbelong. For example, the embodiment of the present invention discloses(1) the method for predicting and coding/decoding the information on thecurrent CU through the information on the CU corresponding to thecurrent CU within the reference frame (the coding method using thetemporal correlation), (2) the method for predicting and coding/decodingthe information on the current CU through the information on the CUneighboring to the current CU within the same frame (the coding methodusing the spatial correlation), and (3) the method for predicting andcoding/decoding the information on the current CU through the predictionstructure in the frame unit (the coding method using the predictionstructure). The (1) to (3) methods select and apply the methodappropriate for the information on the CU or the (1) to (3) methods maybe adaptively applied.

Hereinafter, the embodiments of the present invention will be describedin detail with reference to the accompanying drawings.

Embodiment 1

Method for predicting and coding the information on the current CUthrough the information on the CU corresponding to the current CU withinthe reference frame

FIG. 7 is a diagram schematically explaining the correspondencerelationship between the CU within the current frame and the CU of thereference frame. Referring to FIG. 7, when the information on thecurrent CU 710 of a current frame 700 is coded, the information on theCU 710 to be currently coded through the information on a CU 730corresponding to the current CU 710 among the CUs of a reference frame720 may be predicted and coded. Further, among the CUs of the referenceframe 720, information variation of the current CU 710 for theinformation on the CU 730 corresponding to the current CU 710 may becoded.

As described above, the information on the current CU is coded by usingthe information on the CU corresponding to the current CU within thereference frame, thereby improving the compression efficiency of theinformation on the CU.

Herein, the reference frame, which is an already coded frame before thecurrent frame, means a frame used for temporal coding of the currentframe. Here, the CU may include the CU in the smallest unit from theLCU. Further, the information on the CU to be predicted may include allthe information within the CU. For example, the information on the CUmay include the CU, a prediction unit (PU), a transform unit (TU) splitflag, information on the intra prediction or the inter prediction, modeinformation on the inter prediction on the merge skip, the merge, themotion vector prediction (MVP), or the like, a motion vector, areference picture index, weighted prediction information, predictionmode information on the intra prediction, remaining mode informationamong the prediction mode information on the intra prediction, discretecosine transform (DCT)/discrete sine transform (DST), information on atransform method of quantization parameter, or the like, information onan entropy coding method, or the like.

FIG. 8 is a flow chart schematically explaining an example of a methodfor predicting and coding the information on the current CU by usinginformation on a neighboring CU in a system to which the embodiment ofthe present invention is applied. In the example of FIG. 8, the methodfor predicting and coding the information on the current CU by using theinformation on the CU corresponding to the current CU within thereference frame will be described.

Referring to FIG. 8, when the information on the current CU is coded,the coder predicts the information on the current CU through theinformation on the CU corresponding to the current CU within thereference frame (S810).

The coder determines whether the predicted information is the same asthe information on the current CU (S820) and when the predictedinformation is the same as the information on the current CU, only theprediction flag is coded and transmitted (S830). In this case, the valueof the prediction flag to be coded becomes a value (for example, ‘1’)indicating that the predicted information is the same as the informationon the current CU.

When the predicted information is not the same as the information on thecurrent CU, the prediction flag (for example, the value of theprediction flag may be ‘0’) indicating that the two information are notthe same as each other is coded and transmitted (S840). As such, whenthe predicted information is not the same as the information on thecurrent CU, the information on the current CU is coded and transmittedtogether with the prediction flag indicating the case (S850).

When the information on the current CU is not the same as theinformation on the CU, various methods as described below may be appliedto code and transmit the information on the current CU.

(1) Only the difference value between the information on the current CUand the information on the predicted CU may be coded.

(2) The codeword may be again generated and then, the information on thecurrent CU may be coded, excluding the information on the predicted CUamong the number of several cases relating to the information on thecurrent CU. For example, the information on the predicted CU that may beselected as the information on the current CU may be coded using theremaining candidates, while being excluded from candidates that may beselected as the information on the current CU.

(3) The probability for the information on the current CU may be againgenerated through the information on the predicted CU to code theinformation on the current CU.

In addition to the above-mentioned (1) to (3) methods, when theinformation on the current CU is different from the information on thepredicted CU, various methods may be applied as the method for codingthe information on the current CU.

The method described in FIG. 8 may also be applied to the decodingprocess, in the same method as described above.

FIG. 9 is a flow chart schematically explaining an example of a methodfor predicting and decoding the information of the current CU by usinginformation on the neighboring CU in a system to which the embodiment ofthe present invention is applied. In the example of FIG. 9, the methodfor predicting and decoding the information on the current CU by usingthe information on the CU corresponding to the current CU within thereference frame will be described.

Referring to FIG. 9, the decoder decodes the prediction flag so as todecode the information on the current CU (S910). The prediction flag maybe coded by the coder and may be transmitted as the bitstream.

The decoder determines whether the value of the prediction flag is 1,that is, the prediction flag indicates that the information on thecurrent CU is the same as the predicted information (S920). When thevalue of the prediction flag is 1, the information on the current CU ispredicted from the CU corresponding to the current CU within thereference frame (S930). The decoder generates the information on the CUpredicted from the CU corresponding to the current CU within thereference frame and substitutes the information on the generated CU intothe information on the current CU (S940). That is, the information onthe predicted CU is used as the information on the current CU.

When the value of the prediction flag is 0, the decoder decodes theinformation on the current CU without using the information on theneighboring CU (S950).

When the value of the prediction flag does not indicate that theinformation on the current CU is the same as the predicted information,the information on the current CU may be decoded by various methods asdescribed below.

(1) The CU may be used as the information on the current CU by decodingonly the difference value between the information on the current CU andthe information on the predicted CU and adding the information on thepredicted CU and the difference value and substituting it into theinformation on the current CU.

(2) The codeword may be again generated and then, the information on thecurrent CU may be decoded, excluding the information on the predicted CUamong the number of several cases relating to the information on thecurrent CU. For example, the information on the current CU may bedecoded by the method for selecting the information to be used as theinformation on the current CU from the remaining candidates among thecandidates that may be selected as the information on the current CU,excluding the information on the predicted CU.

(3) The probability for the information on the current CU may be againgenerated through the information on the predicted CU to decode theinformation on the current CU.

In addition to the above-mentioned (1) to (3) methods, various methodsmay be applied as the method for decoding the information on the currentCU.

As the embodiment of the present invention described in FIGS. 8 and 9,when coding the split flat of the LCU, the method for predicting andcoding the split flag regarding the current LCU through the split flagregarding the LCU within the reference frame may be considered.

Actually, comparing the CU of the reference frame with the CU of thecurrent frame, the split flat of both CUs is very similar in most cases.

FIG. 10 is a diagram for explaining the case of predicting theinformation on the current LCU through the information on the LCUcorresponding to the current LCU within the reference frame. FIG. 10Ashows the split flat of the LCU corresponding to the current LCU withinthe reference frame. FIG. 10B shows the split flag of the LCU of thecurrent frame. Both of the LCUs of FIGS. 10A and 10B show the splitdistribution of 64×64 pixels, by way of example. Referring to FIG. 10,it can be confirmed that the split flag for the CU of the referenceframe is similar to the split flag for the CU of the current frame.

FIG. 11 is a diagram schematically explaining a method for transmittingthe split flag. In FIG. 11, when the split_flag of the split flag is 1,it indicates that the corresponding block is split and when thesplit_flag of the split flat is 0, it indicates that the correspondingblock is not split.

The example of FIG. 11 shows the split flag regarding the LCU shown inFIG. 10A. Referring to FIG. 11, it can be appreciated that the splitflag for the CU of the current frame is transferred at each CU level,regardless of the split structure of the reference frame.

In connection with this, the split flag for the current frame can bepredicted and coded by using the split structure of the reference framein the embodiment of the present invention.

FIG. 12 is a diagram schematically explaining a method for predictingthe split flag regarding the current LCU by using split flag regardingLCU corresponding to the current LCU in the reference frame, in thesystem to which the present invention is applied. The example of FIG. 12shows the split flag regarding the LCU shown in FIG. 10B.

The split prediction information, which is the largest CU (LCU) unit atdepth ‘0’, may be used as the information indicating that the split flagof the current CU is the same as that of the CU of the reference frame.The split flag may be predicted in the depth unit.

In the example of FIG. 12, since the spilt flag regarding the LCU ofFIGS. 11A and 11B for the depth 0 is different, ‘0’ is transmitted asthe split prediction information at the depth ‘0’.

The split flag is predicted by increasing the depth ‘1’. Comparing thesplit distribution in a unit of the four CUs of 32×32 pixels having thedepth ‘1’ with the CU of the reference frame, ‘1’ is transferred to thesplit prediction information when they have the same split distributionand ‘0’ is transferred when they do not have the same splitdistribution. Since the CU of 32×32 pixels at the upper left end doesnot have the same split distribution, ‘0’ is transferred to the splitprediction information. Meanwhile, the CU of 32×32 pixels at the upperright end has the same split distribution, ‘1’ is transferred to thesplit prediction information.

When the spilt prediction information is ‘1’, the split distribution ofthe CU within the reference frame may be applied to the current CU andthe split flag regarding the CU for a depth deeper than the currentdepth may not be transferred. Next, ‘1’ is stored as the splitprediction information of the CU of 32×32 pixels at the lower left endand ‘0’ is stored as the split prediction information of the CU of 32×32pixels at the lower left end.

The split flag may be coded by the hierarchical method performing theprediction in a smaller unit CU by increasing the depth by ‘1’ by theabove-mentioned method only when the split prediction information is 0.

Embodiment 2

Method for Predicting and Coding the Information on the Current CUThrough the Information on the Neighboring CU within the Same Frame

FIG. 13 is a diagram schematically showing the current CU and theneighboring CU within the same frame.

In the high efficiency video coding, when the information on the currentCU is coded, the compression efficiency of the information on the CU canbe improved by predicting and coding the information on the current CUthrough the information on the CU neighboring to the current CU withinthe frame as shown in FIG. 13 or coding the information variation on thecurrent CU for the information on the CU neighboring to the current CU.

Here, the CU may include the CU in the smallest unit from the LCU.Further, the information on the CU may include all the informationwithin the CU. For example, the information on the CU may include theCU, a prediction unit (PU), a transform unit (TU) split flag,information on the intra prediction or the inter prediction, modeinformation on the inter prediction on the merge skip, the merge, themotion vector prediction (MVP), or the like, a motion vector, areference picture index, weighted prediction information, predictionmode information on the intra prediction, remaining mode informationamong the prediction mode information on the intra prediction, discretecosine transform (DCT)/discrete sine transform (DST), information on atransform method of quantization parameter, or the like, information onan entropy coding method, or the like.

Further, the information on the CU may be coded by adaptively selectingembodiment 1 and embodiment 2 in the CU unit and the information on theCU may be coded in consideration of both of the embodiments.

FIG. 14 is a flow chart for schematically explaining a method forpredicting and coding information on the current CU through CUneighboring to the current CU when coding the information on the currentCU according to the exemplary embodiment of the present invention.

Referring to FIG. 14, when the information on the current CU is coded,the coder predicts the information on the current CU through theinformation on the already coded CU neighboring to the current CU togenerate the prediction information (S1410).

The coder determines whether the information on the current CU is thesame as the predicted CU information (S1420). When the information onthe current CU is the same as the predicted CU information, the codertransfers the prediction flag ‘1’ indicating that the information on thecurrent CU is the same as the predicted CU (S1430). When the informationon the current CU is not the same as the predicted CU information, thecoder codes and transmits the prediction flag into the value of ‘0’(S1440) and at the same time, codes and transmits the information on thecurrent CU (S1450).

Here, when the information on the current CU is not the same as theinformation on the predicted CU, the information on the current CU maybe coded by various methods as described below.

(1) Only the difference value between the information on the current CUand the information on the predicted CU may be coded.

(2) The codeword may be again generated and then, the information on thecurrent CU may be coded, excluding the information on the predicted CUamong the number of several cases relating to the information on thecurrent CU. For example, the information on the predicted CU that may beselected as the information on the current CU may be coded using theremaining candidates, while being excluded from candidates that may beselected as the information on the current CU.

(3) The probability for the information on the current CU may be againgenerated through the information on the predicted CU to code theinformation of the current CU.

In addition to this, when the information on the current CU is not thesame as the information on the predicted CU, the information on thecurrent CU can be coded using various methods.

The method described in FIG. 14 may be similarly applied even when thedecoding is performed.

FIG. 15 is a flow chart schematically explaining another example of amethod for predicting and decoding the information on the current CU byusing the information on the neighboring CU in a system to which theembodiment of the present invention is applied. In the example of FIG.15, the method for predicting and decoding the information on thecurrent CU by using the information on the CU neighboring to the currentCU within the current frame will be described.

Referring to FIG. 15, the decoder decodes the prediction flag so as todecode the information on the current CU (S1510). The prediction flagmay be coded by the coder and may be transmitted as the bitstream.

The decoder determines whether the value of the prediction flag is 1,that is, the prediction flag indicates that the information on thecurrent CU is the same as the predicted information (S1520). When thevalue of the prediction flag is 1, the information on the current CU ispredicted from the CU neighboring to the current CU (S1530). The decodergenerates the information on the CU predicted from the CU neighboring tothe current CU and substitutes the information on the generated CU intothe information on the current CU (S1540). That is, the information onthe predicted CU is used as the information on the current CU.

When the value of the prediction flag is 0, the decoder decodes theinformation on the current CU without using the information on theneighboring CU (S1550).

As described above, the information on the current CU that may bedecoded using the information on the neighboring CU may include the CU,a prediction unit (PU), a transform unit (TU) split flag, information onthe intra prediction or the inter prediction, mode information on theinter prediction on the merge skip, the merge, the motion vectorprediction (MVP), or the like, a motion vector, a reference pictureindex, weighted prediction information, prediction mode information onthe intra prediction, remaining mode information among the predictionmode information on the intra prediction, discrete cosine transform(DCT)/discrete sine transform (DST), information on a transform methodof quantization parameter, or the like, information on an entropy codingmethod, or the like.

For example, when the current CU is the intra prediction mode, if thetarget information to be decoded relates to the intra prediction mode ofthe current CU, the prediction flag may be a flag indicating whether thecurrent CU is coded by the intra prediction mode of the neighboring CU.Therefore, in this case, provided that the above-mentioned S1520 to 1550are applied, the current CU may be predicted according to the intraprediction mode of the neighboring CU when the value of the decodedprediction flag is 1 and the current CU may be predicted according toanother intra prediction mode, not the intra prediction mode of theneighboring CU, when the value of the decoded prediction flag is 0.

When the value of the prediction flag does not indicate that theinformation on the current CU is the same as the predicted information,the information on the current CU may be decoded by various methods asdescribed below.

(1) The difference value between the current CU information and thepredicted CU information may be decoded. By adding the information onthe predicted CU and the difference value and substituting it into theinformation on the current CU, the information derived by the additioncan be used as the current CU information.

(2) The codeword may be again generated and then, the information on thecurrent CU may be decoded, excluding the information on the predicted CUamong the number of several cases relating to the information on thecurrent CU. For example, the information on the current CU may bedecoded by the method for selecting the information to be used as theinformation on the current CU from the remaining candidates among thecandidates that may be selected as the information on the current CU,excluding the information on the predicted CU. For example, when thecurrent CU is the intra prediction mode, if the target information to bedecoded relates to the intra prediction mode of the current CU, thecurrent CU may be predicted according to another intra prediction mode,not the intra prediction mode of the neighboring CU, in the case inwhich the value of the prediction flag is 0, that is, making the intraprediction mode of the current CU and the intra prediction mode of theneighboring CU different from each other is indicated by the predictionflag.

(3) The probability for the information on the current CU may be againgenerated through the information on the predicted CU to decode theinformation on the current CU.

In addition to the above-mentioned (1) to (3) methods, various methodsmay be applied as the method for decoding the information on the currentCU.

FIG. 16 is a diagram explaining one predicting and coding theinformation on the current CU by using the neighboring CU. FIG. 16 showsthe split distribution of two neighboring 64×64 LCUs 1610 and 1620.According to the embodiment of the present invention, it is possible touse the information on the LCU 1620 when the LCU 1610 is coded.

Since the maximum CU of the LCU 1620 is 16×16 pixels and the minimum CUis 8×8 pixels, the current LCU 1610 may define the maximum CU and theminimum CU may be defined, like the LCU 1620. For example, when thecurrent LCU 1610 is coded, the split flag is coded starting from the UCin a unit of 64×64 pixels. In this case, the LCU 1620 is not the CU in aunit of 64×64 pixels, such that that the current CU is hardly likely tobecome a unit of 64×64 pixels. Therefore, the split flag regarding thecurrent CU may not be transmitted by spatially predicting the splitflag.

Embodiment 3

Method for Predicting and Coding the Information on the Current CUThrough the Prediction Structure

In the case of the high efficiency video coding, when the CU informationis coded, the compression efficiency can be improved by coding the CUinformation by predicting the information on the CU to be currentlyprovided through the prediction structure. Herein, the CU may includethe CU in the smallest unit from the LCU and the CU information mayinclude all the information within the CU.

FIG. 17 is a flow chart schematically explaining an example of a methodfor predicting and coding the information on the current CU from theprediction structure when coding the information on the current CUaccording to the embodiment of the present invention.

Referring to FIG. 17, when the current CU information is coded, thecoder predicts the information on the current CU through the informationon the already coded CU neighboring to the current CU through theprediction structure to generate the prediction information (S1710).

The coder determines whether the information on the current CU is thesame as the predicted CU information (S1720). When the information onthe current CU is the same as the information on the predicted CU, thecoder transmits the prediction flag ‘1’ indicating that the informationon the current CU is the same as the predicted CU (S1730). When theinformation on the current CU is not the same as the information on thepredicted CU, the coder codes and transmits the prediction flag into thevalue of ‘0’ (S1740) and at the same time, codes and transmits theinformation on the current CU (S1750).

Here, when the information on the current CU is not the same as theinformation on the predicted CU, the information on the current CU maybe coded by various methods as described below.

(1) Only the difference value between the information on the current CUand the information on the predicted CU may be coded.

(2) The codeword may be again generated and then, the information on thecurrent CU may be coded, excluding the information on the predicted CUamong the number of several cases relating to the information on thecurrent CU. For example, the information on the predicted CU that may beselected as the information on the current CU may be coded using theremaining candidates, while being excluded from candidates that may beselected as the information on the current CU.

(3) The probability for the information on the current CU may be againgenerated through the information on the predicted CU to code theinformation on the current CU.

In addition to this, when the information on the current CU is not thesame as the information on the predicted CU, the information on thecurrent CU can be coded using various methods.

The method described in FIG. 17 may be similarly applied even when thedecoding is performed.

FIG. 18 is a flow chart schematically explaining an example of a methodfor predicting and decoding the information on the current CU by usingthe prediction structure to which the embodiment of the presentinvention is applied.

Referring to FIG. 18, the decoder decodes the prediction flag so as todecode the information on the current CU (S1810). The prediction flagmay be coded by the coder and may be transmitted as the bitstream.

The decoder determines whether the value of the prediction flag is 1,that is, the prediction flag indicates that the information on thecurrent CU is the same as the predicted information (S1820). When thevalue of the prediction flag is 1, the information on the current CU ispredicted from the prediction structure (S1830). The decoder generatesthe information on the CU predicted from the prediction structure andsubstitutes the information on the generated CU into the information onthe current CU (1840). That is, the information on the predicted CU isused as the information on the current CU.

When the value of the prediction flag is 0, the decoder decodes theinformation on the current CU without using the prediction structure(S1850).

When the value of the prediction flag does not indicate that theinformation on the current CU is the same as the predicted information,the information on the current CU may be decoded by various methods asdescribed below.

(1) The difference value between the current CU information and thepredicted CU information may be decoded. By adding the information onthe predicted CU and the difference value and substituting it into theinformation on the current CU, the information derived by the additioncan be used as the current CU information.

(2) The codeword may be again generated and then, the information on thecurrent CU may be decoded, excluding the information on the predicted CUamong the number of several cases relating to the information on thecurrent CU. For example, the information on the current CU may bedecoded by the method for selecting the information to be used as theinformation on the current CU from the remaining candidates among thecandidates that may be selected as the information on the current CU,excluding the information on the predicted CU.

(3) The probability for the information on the current CU may be againgenerated through the information on the predicted CU to decode theinformation on the current CU.

In addition to the above-mentioned (1) to (3) methods, various methodsmay be applied as the method for decoding the information on the currentCU.

FIG. 19 is a diagram explaining one predicting and coding theinformation on the current CU by the prediction structure in a frameunit according to the embodiment of the present invention when includinga hierarchical prediction structure.

Referring to FIG. 19, when B frame, that is, the number 4 frame T4 ispredicted and coded through the number 0 frame T0 and the number 8 frameT8, the information on the CU to be currently coded may be predictedthrough the prediction structure in the frame unit.

When the prediction is performed through two lists by referring to thetemporally previous frame from the current frame and the temporallysubsequent frame, respectively, all the CUs within the number 4 frame T4designates L0 as the number 0 frame T0 and L1 as the number 8 frame T8.Since this has the hierarchical prediction structure in the frame unit,when the list is 1, the number 0 frame T0 or the number 8 frame T8 maybe designated as the reference frame, respectively, but when the list istwo, only the two reference frames are present. Therefore, the L0designates the temporally previous frame as the reference frame and theL1 designates the temporally subsequent frame as the reference frame. Inthe case of the prediction structure shown in FIG. 19, many CUs performthe prediction by using two lists by referring to the temporallyprevious frame and the temporally subsequent frame, respectively.Therefore, when the reference index designating the reference frame isstored within the CU information, the reference index for each list isnot transmitted in the case in which the prediction is performed by twolists by referring to the temporally previous frame and the temporallysubsequent frame, respectively, and only the information correspondingto the case in which the prediction is performed by two lists byreferring to the temporally previous frame and the temporally subsequentframe, respectively, is transmitted. In other cases, the compressionefficiency for coding the reference index may be improved bytransmitting the reference index of the corresponding list, togetherwith the information that does not correspond to the case in which theprediction is performed by two lists by referring to the temporallyprevious frame and the temporally subsequent frame, respectively.

FIG. 20 is a flow chart schematically explaining an example of a methodfor decoding reference index prediction information according to theembodiment of the present invention.

Referring to FIG. 20, the decoder decodes the reference index predictionflag received from the coder (S2010). When the prediction is performedby two lists by referring to the temporally previous frame and thetemporally subsequent frame, respectively, the value of the decodedreference index prediction flag represents 1. In other cases, the valueof the decoded reference index prediction flag represents 0.

The decoder determines whether the value of the reference indexprediction flag represents 1 (S2020) and when the value of the referenceindex prediction flag is 1, the reference index is predicted through theprediction structure (S2030). The decoder designates the temporallyprevious frame and the temporally subsequent frame, respectively, as thereference index in the L0 and the L1 through the prediction structure(S2040). In addition, when the reference index prediction flag is 0, thedecoder decodes the reference index corresponding to the list by theexisting method (S2050).

FIG. 21 is a diagram showing a schematic configuration of a coder forpredicting and coding the information on the current CU through theinformation on the CU corresponding to the current CU within thereference frame according to the embodiment of the present invention.

Referring to FIG. 21, a coder 2100 includes a CU information predictionmodule 2110, a determination module 2120, and a CU information codingmodule 2130.

The CU information prediction module 2110 receives the information onthe CU corresponding to the current CU within the reference frame tooutput the predicted CU information.

The determination module 2120 receives the information on the current CUand the CU information predicted in the CU information prediction module2110 to determine whether the information on the current CU is the sameas the information on the predicted CU and transmits the prediction flaginformation according to the determination result. When the informationon the current CU is the same as the information on the predicted CU,the transmitted prediction flag information is set to be ‘1’.

When the transmitted prediction flag information is ‘1’, the predictionflag information is coded without separately coding the information onthe current CU and is transmitted through the bitstream.

When the information on the current CU is not the same as theinformation on the predicted CU, the prediction flag information to betransmitted is set to be ‘0’.

When the prediction flag information to be transmitted is ‘0’, the CUinformation coding module 2130 may code the information on the currentCU by using the CU information predicted in the CU informationprediction module 2110. The CU information coded in the CU informationcoding module 2130 is transmitted to the decoder, being included in thebitstream.

FIG. 22 is a diagram showing a schematic configuration of a decoder forpredicting and decoding the information on the current CU through theinformation on the CU corresponding to the current CU within thereference frame according to the embodiment of the present invention.

Referring to FIG. 22, the decoder 2200 includes a prediction flagdecoding module 2210, a CU information prediction module 2220, and a CUinformation decoding module 2230.

When the bitstream is transmitted, the prediction flag decoding module2210 decodes the prediction flag information.

The CU information prediction module 2120 performs the predictionthrough the information on the CU corresponding to the current CU.

When the value of the decoded prediction flag information is ‘1’, thevalue predicted through the information on the CU corresponding to thecurrent CU is stored as the information on the current CU within thereference frame.

When the value of the decoded prediction flag information is ‘0’, the CUinformation decoding module 2130 decodes the information on the coded CUtransmitted within the bitstream and is stored as the information on thecurrent CU. In this case, the CU information decoding module 2130 maydecode the information on the current CU by using the CU informationpredicted in the CU information prediction module 2120.

FIG. 23 is a diagram showing another example of a coder for predictingand coding the information on the current CU through the information onthe CU corresponding to the current CU within the reference frameaccording to the embodiment of the present invention. In FIG. 23, thecoder predicts and codes the split flag regarding the current CU throughthe CU corresponding to the current CU within the reference frame.

Referring to FIG. 23, the coder 2300 includes a CU split flag predictionmodule 2310, a determination module 2320, and a CU split flag codingmodule 2330.

The CU split flag prediction module 2310 receives the split flagregarding the CU corresponding to the current CU within the referenceframe to output the predicted CU split flag.

The determination module 2320 receives the split flag regarding thecurrent CU and the CU split flag predicted in the CU split flagprediction module 2310 to determine whether the split flag regarding thecurrent CU is the same as the predicted CU split flag and transmits thesplit prediction flag information according to the determination result.When the split flag regarding the current CU is the same as thepredicted CU split flag, the transmitted prediction flag information isset to be ‘1’.

When the transmitted prediction flag information is ‘1’, the splitprediction flag information is coded without separately coding the splitflag regarding the current CU and is transmitted through the bitstream.

When the split flag regarding the current CU is not the same as thepredicted CU split flag, the split prediction information to betransmitted is set to be ‘0’.

When the split prediction flag information to be transmitted is ‘0’, theCU split flag coding module 2330 may code the split flag regarding thecurrent CU by using the CU split flag predicted in the CU splitinformation prediction module 2310. The CU split flag decoded in the CUsplit flag decoding module 2330 is transmitted to the decoder, beingincluded in the bitstream together with the prediction flag information.

FIG. 24 is a diagram showing another example of a decoder for predictingand decoding the information on the current CU through the informationon the CU corresponding to the current CU within the reference frameaccording to the embodiment of the present invention. In FIG. 23, thedecoder predicts and decodes the split flag regarding the current CUthrough the CU corresponding to the current CU within the referenceframe.

Referring to FIG. 24, the decoder 2400 includes a split prediction flagdecoding module 2410, a CU split flag prediction module 2420, and a CUsplit flag decoding module 2430.

When the bitstream is transmitted, the split prediction flag decodingmodule 2410 decodes the split prediction flag information.

The CU split flag prediction module 2420 receives the split flagregarding the current CU through the information on the CU correspondingto the current CU within the reference frame.

When the value of the decoded split prediction flag information is ‘1’,the value predicted through the information on the CU corresponding tothe current CU is stored as the split flag regarding the current CUwithin the reference frame.

When the value of the decoded split prediction flag information is ‘0’,the CU split flag decoding module 2430 decodes the split flag regardingthe coded CU transmitted within the bitstream and is stored as the splitflag regarding the current CU. In this case, the CU split flag decodingmodule 2430 may decode the split flag regarding the current CU by usingthe CU split flag predicted in the CU split flag prediction module 2420.

FIG. 25 is a diagram schematically showing a configuration of the coderfor predicting and coding the information on the current CU by using theinformation on the neighboring CU within the same frame according to theembodiment of the present invention.

Referring to FIG. 25, a coder 2500 includes a CU information predictionmodule 2510, a determination module 2520, and a CU information codingmodule 2530.

The CU information prediction module 2510 receives the information onthe CU neighboring to the current CU to output the predicted CUinformation.

The determination module 2520 receives the information on the current CUand the CU information predicted in the CU information prediction module2510 to determine whether the information on the current CU is the sameas the information on the predicted CU and transmits the prediction flaginformation according to the determination result. When the informationon the current CU is the same as the information on the predicted CU,the transmitted prediction flag information is set to be ‘1’.

When the transmitted predict flag information is ‘1’, the predictionflag information is coded without separately coding the information onthe current CU and is transmitted through the bitstream.

When the information on the current CU is not the same as theinformation on the predicted CU, the prediction flag information to betransmitted is set to be ‘0’.

When the prediction flag information to be transmitted is ‘0’, the CUinformation coding module 2530 may code the information on the currentCU by using the CU information predicted in the CU informationprediction module 2510. The CU information coded in the CU informationcoding module 2530 is transmitted to the decoder, being included in thebitstream together with the prediction flag information.

FIG. 26 is a diagram schematically showing a configuration of thedecoder for predicting and decoding the information on the current CU byusing the information on the neighboring CU within the same frameaccording to the embodiment of the present invention.

Referring to FIG. 26, a decoder 2600 includes a prediction flag decodingmodule 2610, a CU information prediction module 2620, and a CUinformation decoding module 2630.

When the bitstream is transmitted, the prediction flag decoding module2610 decodes the prediction flag information.

The CU information prediction module 2620 predicts the information onthe current CU through the information on the CU neighboring to thecurrent CU.

When the value of the decoded prediction flag information is ‘1’, thevalue predicted through the information on the CU neighboring to thecurrent CU is stored as the information on the current CU.

When the value of the decoded prediction flag information is ‘0’, the CUinformation decoding module 2630 decodes the information on the coded CUtransmitted within the bitstream and is stored as the information on thecurrent CU. In this case, the CU information decoding module 2630 maydecode the information on the current CU by using the CU informationpredicted in the CU information prediction module 2620.

FIG. 27 is a diagram schematically showing a configuration of the coderfor predicting and decoding the information on the current CU throughthe prediction structure according to the embodiment of the presentinvention.

Referring to FIG. 27, a coder 2700 includes a CU information predictionmodule 2710, a determination module 2720, and a CU information codingmodule 2730.

The CU information prediction module 2710 receives the predictionstructure to output the predicted CU information. The input predictionstructure is as described in FIG. 6 and FIG. 19.

The determination module 2720 receives the information on the current CUand the CU information predicted in the CU information prediction module2710 to determine whether the information on the current CU is the sameas the information on the predicted CU and transmits the prediction flaginformation according to the determination result. When the informationon the current CU is the same as the information on the predicted CU,the transmitted prediction flag information is set to be ‘1’.

When the transmitted predict flag information is ‘1’, the predictionflag information is coded without separately coding the information onthe current CU and is transmitted through the bitstream.

When the information on the current CU is not the same as theinformation on the predicted CU, the prediction flag information to betransmitted is set to be ‘0’.

When the prediction flag information to be transmitted is ‘0’, the CUinformation coding module 2730 may code the information on the currentCU by using the CU information predicted in the CU informationprediction module 2710. The CU information coded in the CU informationcoding module 2730 is transmitted to the decoder, being included in thebitstream together with the prediction flag information.

FIG. 28 is a diagram schematically showing a configuration of the coderfor predicting and decoding the information on the current CU throughthe prediction structure according to the embodiment of the presentinvention.

Referring to FIG. 28, a decoder 2800 includes a prediction flag decodingmodule 2810, a CU information prediction module 2820, and a CUinformation decoding module 2830.

When the bitstream is transmitted, the prediction flag decoding module2810 decodes the prediction flag information.

The CU information prediction module 2820 predicts the information onthe current CU through the prediction structure. Here, the predictionstructure used for the prediction is as described in FIG. 6 and FIG. 19.

When the value of the decoded prediction flag information is ‘1’, theinformation on the CU predicted through the prediction structure isstored as the information on the current CU.

When the value of the decoded prediction flag information is ‘0’, the CUinformation decoding module 2830 decodes the information on the coded CUtransmitted within the bitstream and is stored as the information on thecurrent CU. In this case, the CU information decoding module 2830 maydecode the information on the current CU by using the CU informationpredicted in the CU information prediction module 2820.

In the above-mentioned exemplary system, although the methods havedescribed based on a flow chart as a series of steps or blocks, thepresent invention is not limited to a sequence of steps but any step maybe generated in a different sequence or simultaneously from or withother steps as described above. Further, it may be appreciated by thoseskilled in the art that steps shown in a flow chart is non-exclusive andtherefore, include other steps or deletes one or more steps of a flowchart without having an effect on the scope of the present invention.

The above-mentioned embodiments include examples of various aspects.Although all possible combinations showing various aspects are notdescribed, it may be appreciated by those skilled in the art that othercombinations may be made. Therefore, the present invention should beconstrued as including all other substitutions, alterations andmodifications belong to the following claims.

The invention claimed is:
 1. A method for decoding video information,the method comprising: decoding a prediction flag indicating whetherinformation of a current coding unit is the same as predictioninformation derived from information of a reference block correspondingto the current coding unit; deriving the information of the currentcoding unit based on the decoded prediction flag; and performinginter-prediction of the current coding unit using the derivedinformation of the current coding unit, wherein the information of thecurrent coding unit includes information on a motion vector of thecurrent coding unit, wherein the prediction information includesprediction information on a motion vector, wherein, when the predictionflag indicates the information of the current coding unit is the same asprediction information derived from information of the reference block,a first reference index and a second reference index is determined to bea predetermined constant value based on whether two lists of referenceframes are corresponded to the current coding unit, wherein the currentcoding unit is decoded based on a first frame and a second frame,wherein the first frame is determined by the first reference index andfirst list of reference frames, wherein the second frame is determinedby the second reference index and second list of reference frames, andwherein the predetermined constant value is set before decoding thevideo information.
 2. The method of claim 1, the method furthercomprising generating an occurrence probability for entropy decoding ofa split flag of the current coding unit, and performing the entropydecoding of the split flag of the current coding unit according to thegenerated occurrence probability, wherein the generation of theoccurrence probability relating to the split flag of the current codingunit is dependent on a split depth value of a neighboring coding unit,wherein the neighboring coding unit is determined to be at least one ofcoding units located at a top side or a left side of the current codingunit, wherein the split flag indicates whether a coding unit is splitand the split depth value indicates a depth value of a coding unitaccording to the split flag.
 3. A method for encoding video information,the method comprising: deriving prediction information from informationof a reference block corresponding to a current coding unit; determiningwhether information of the current coding unit is the same as theprediction information; and encoding a prediction flag of the currentcoding unit based on the result of determination; wherein theinformation of the current coding unit includes information on a motionvector of the current coding unit, wherein the prediction informationincludes prediction information on a motion vector, wherein, when theprediction flag indicates the information of the current coding unit isthe same as prediction information derived from information of thereference block, a first reference index and a second reference index isdetermined to be a predetermined constant value based on whether twolists of reference frames are corresponded to the current coding unit,wherein the current coding unit is encoded based on a first frame and asecond frame, wherein the first frame is determined by the firstreference index and first list of reference frames, wherein the secondframe is determined by the second reference index and second list ofreference frames, and wherein the predetermined constant value is setbefore encoding the video information.
 4. A non-transitory recordingmedium storing a bitstream generated by a method for encoding videoinformation, the method comprising: deriving prediction information frominformation of a reference block corresponding to a current coding unit;determining whether information of the current coding unit is the sameas the prediction information; and encoding a prediction flag of thecurrent coding unit based on the result of determination; wherein theinformation of the current coding unit includes information on a motionvector of the current coding unit, wherein the prediction informationincludes prediction information on a motion vector, wherein, when theprediction flag indicates the information of the current coding unit isthe same as prediction information derived from information of thereference block, a first reference index and a second reference index isdetermined to be a predetermined constant value based on whether twolists of reference frames are corresponded to the current coding unit,wherein the current coding unit is encoded based on a first frame and asecond frame, wherein the first frame is determined by the firstreference index and first list of reference frames, wherein the secondframe is determined by the second reference index and second list ofreference frames, and wherein the predetermined constant value is setbefore encoding the video information.